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Eighty-six countries won medals at the 2016 Olympics in Rio de Janeiro. Based on the results: 1 country won more than 100 medals 2 countries won between 51 and 100 medals 3 countries won between 31 and 50 medals 4 countries won between 21 and 30 medals 15 countries won between 11 and 20 medals 15 countries won between 6 and 10 medals 46 countries won between 1 and 5 medals Suppose one of the 86 countries winning medals at the 2016 Olympics is selected at random. a. What is the probability that the selected country won more than 50 medals? b. What is the probability that the selected country did not win more than 100 medals? c. What is the probability that the selected country won 10 or fewer medals? d. What is the probability that the selected country won between 11 and 50 medals?

Short Answer

Expert verified
a. The probability that the selected country won more than 50 medals is \(\frac{3}{86}\). b. The probability that the selected country did not win more than 100 medals is \(\frac{85}{86}\). c. The probability that the selected country won 10 or fewer medals is \(\frac{61}{86}\). d. The probability that the selected country won between 11 and 50 medals is \(\frac{22}{86}\).

Step by step solution

01

Understanding probability and frequency distributions

Probability can be calculated as the ratio of the number of successful outcomes to the total number of possible outcomes. In this case, the possible outcomes are the 86 countries that won medals, and the successful outcomes depend on the conditions specified in each part of the question. A frequency distribution is a way to represent data by showing how often (frequency) different values of a variable occur. From the exercise, we already have the frequency distribution of medals won by the 86 countries:
02

Calculate the probabilities for part a

We're asked to find the probability that a randomly selected country won more than 50 medals. This occurs for 1 + 2 = 3 countries (1 country won more than 100 medals and 2 countries won between 51 and 100 medals). Hence, the successful outcome is 3. The probability is calculated as the ratio of successful outcomes over total outcomes, or in this case, \(\frac{3}{86}\). Therefore, the probability that the selected country won more than 50 medals is \(\frac{3}{86}\).
03

Calculate the probabilities for part b

We are asked to find the probability that the selected country did not win more than 100 medals. This scenario occurs for every country except the 1 country that won more than 100 medals. So, the successful outcome is 86 - 1 = 85. The probability is calculated as the ratio of successful outcomes over total outcomes, or in this case, \(\frac{85}{86}\). Therefore, the probability that the selected country did not win more than 100 medals is \(\frac{85}{86}\).
04

Calculate the probabilities for part c

We are asked to find the probability that the selected country won 10 or fewer medals. This occurs for 15 countries that won between 6 and 10 medals and 46 countries that won between 1 and 5 medals, a total of 15 + 46 = 61 countries. The probability is calculated as the ratio of successful outcomes over total outcomes, or in this case, \(\frac{61}{86}\). Therefore, the probability that the selected country won 10 or fewer medals is \(\frac{61}{86}\).
05

Calculate the probabilities for part d

We are asked to find the probability that the selected country won between 11 and 50 medals. This occurs for 3 countries that won between 31 and 50 medals, 4 countries that won between 21 and 30 medals, and 15 countries that won between 11 and 20 medals, a total of 3 + 4 + 15 = 22 countries. The probability is calculated as the ratio of successful outcomes over total outcomes, or in this case, \(\frac{22}{86}\). Therefore, the probability that the selected country won between 11 and 50 medals is \(\frac{22}{86}\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Understanding Frequency Distribution
Frequency distribution is a fundamental concept in statistics that informs us about the spread of data points within a dataset. It provides a visual or tabular representation of how often each value occurs, which is critical in understanding the nature of the data at a glance.

For example, in an Olympic medal tally situation, we can create a frequency distribution table to show how many countries won medals within specific ranges—like 1-5, 6-10, and so on. This tells us not only how many medals were won, but also how these medals are distributed across competing countries.

More formally, the frequency of an event is the number of times that event has occurred, and the distribution helps us organize these frequencies into an understanding of the data's pattern. By analyzing the frequency distribution, one can determine the most common outcomes, rare occurrences, or trends in the data, which is invaluable for making predictions or strategic decisions.
Calculating the Ratio of Successful Outcomes
The ratio of successful outcomes is the backbone of probability calculation. In a statistical context, a 'successful outcome' is defined as an outcome that meets the criteria we're interested in. For instance, when trying to determine the probability of selecting a country that won more than 50 medals from the list of medal winners, the successful outcomes would be the actual instances where this condition is met.

In the Olympic medal tally problem, there are 3 countries that won more than 50 medals, and hence, there are 3 successful outcomes. When we compare this to the total number of outcomes, which in this case is the total number of countries that won medals, we can see how these successful outcomes stack up against the whole. This ratio is the essence of calculating probabilities and offers a quantitative understanding of the likelihood of various events.
The Process of Probability Calculation
Probability calculation involves determining the chance of a specific outcome occurring within a set of possible outcomes. It's expressed as a value between 0 and 1, where 0 indicates impossibility, and 1 represents certainty. In the context of the Olympic medals example, calculating probabilities involves taking the ratio of successful outcomes to the total number of outcomes.

The formula for probability is conventionally understood as: \[ P(E) = \frac{{\text{{number of successful outcomes}}}}{{\text{{total number of outcomes}}}} \] where P(E) represents the probability of event E occurring.

To calculate these probabilities accurately, one must first identify the successful outcomes relevant to the question being asked, and then divide this number by the total number of possible outcomes. By applying this method to different scenarios in the Olympic medals example, we can derive probabilities for various conditions, such as not winning more than 100 medals or winning a swath of 11 to 50 medals. Understanding this process is essential for producing accurate statistical analyses in a wide range of fields.

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Most popular questions from this chapter

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